This invention relates to liquid crystal nematic substances based on new derivatives of 1,3-dioxanes for use in electrooptical components, which can modulate incident or transmitted light as well as exhibit numbers, symbols and images. Electrooptical components of this kind can, for instance, be used as displays in electronic clocks, computer systems and instruments.
The literature discloses a large number of liquid crystal compounds, which are sometimes suggested for use in electro-optical displays: D. Demus, H. Demus and H. Zaschke: Flussige Kristalle in Tabellen, VEB Deutscher Verlag fur Grundstoffindustrie, Leipzig 1974--D. Demus in: "Non-emissive Electrooptic Displays" edited by R. A. Kmetz and F. K. von Willisen Plenum Press New York--London 1976 pp. 83-117--V. V. Titov: Proceedings 3.sup.rd Liquid Crystal Conference of Socialistic Countries, Budapest 1979--G. Weber, P. del Pino, L. Pohl: Proceedings 10. Freiburger Arbeitstagung Flussigkristalle 1980.
No pure compound is known which exhibits all the required properties for use in displays. Therefore, mixtures of several liquid crystal substances are always used. The requirements placed on the mixtures (melting- and clearing point, operating temperature range, threshold voltage, time behavior, temperature dependency of the properties) are increasingly severe, and additionally, new mixtures are required for new areas of use. There is therefore a continuing search for new liquid crystal mixtures to meet these demands.
Derivatives of 1,3-dioxane having the general formula ##STR2## are known for use in electro-optical components (DD-WP 139 867). A large number of such compounds with two six-membered rings are only monotropic liquid crystals, while the compounds with three six-membered rings have comparatively low solubility.